Earlier quoted context omitted.
In 1998, Linux was reliable and performant. It just hadn't made inroads into big corporations to give it pointy-haired-boss cred.
In 1998, Linux was still behind SunOS/Solaris in maturity and even if it had been even, Intel x86 hardware wasn't remotely on par with what Sun machines could do.
There were things that Solaris was better at in 1998: big iron things, NUMA things, fault-tolerance things, what we now call "observability". (I still don't have a good equivalent for pstack on Linux!) But Linux was enormously better at many other things, including, most crucially, networking.
That was about the time the Top500 list started morphing into a list of the top 500 Beowulfs.